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A206922
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Root of the n-th binary palindrome. Least number r > 1 such that A006995(n) can be represented by a finite or infinite number of iterations A006995(A006995(A006995(...(...(r))...).
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1
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2, 2, 3, 4, 4, 6, 4, 8, 6, 10, 11, 12, 13, 14, 4, 16, 8, 18, 19, 20, 6, 22, 23, 24, 25, 26, 10, 28, 29, 30, 11, 32, 12, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 13, 46, 47, 48, 49, 50, 14, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 4, 64, 16, 66, 67, 68
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OFFSET
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1,1
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COMMENTS
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If n is not a binary palindrome, then a(n)=n.
For n>3: a(n)<n, iff n is a binary palindrome.
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LINKS
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FORMULA
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a(n) <= n for n > 1.
a(n)=p(k), where p(k) can be determined by the following iteration: set k=0, p(0)=A006995(n). Repeat while A178225(p(k))==1, set k=k+1, p(k)=A206915(p(k-1)) end repeat [for n<>3].
Recursion for n<>3:
Case 1: a(n)=n, if n is not a binary palindrome;
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EXAMPLE
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PROG
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/* C program fragment, omitting formal details, n!=3 */
k=0;
{
k++;
}
return p;
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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